CMP slurry/method for polishing ruthenium and other films

Abstract

A method and associated composition for CMP processing of noble metal-containing substrates (such as ruthenium-containing substrates) afford both high removal rates of the noble metal and are tunable with respect to rate of noble metal removal in relation to removal of other films. Low levels of an oxidizing agent containing one or more peroxy-functional group(s) can be used along with a novel ligand to effectively polish noble metal substrates.

The invention claimed is: 
     
       1. A system for chemical mechanical polishing comprising:
 a semiconductor substrate having at least a barrier layer comprising a noble metal selected from the group consisting of ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), platinum (Pt), silver (Ag), gold (Au), alloys thereof, oxides thereof, and combinations thereof; 
 a rotating polishing pad attached to a platen; 
 a chemical mechanical planarization polishing composition having a pH which is basic, comprising:
 a) an abrasive; 
 b) a cyanate salt; and 
 c) an oxidizing agent containing at least one peroxy-functional group; wherein the chemical mechanical planarization polishing composition is (a) placed between the barrier layer and the rotating polishing pad; and (b) in contact with at least the noble metal and the rotating polishing pad wherein the rotating polishing pad is able to polish at least the noble metal of the barrier layer. 
 
 
     
     
       2. The system of  claim 1  wherein the cyanate salt is selected from sodium cyanate, potassium cyanate, and ammonium cyanate. 
     
     
       3. The system of  claim 1  wherein the oxidizing agent is selected from periodic acid and a salt of periodic acid. 
     
     
       4. The system of  claim 3  wherein the salt of periodic acid is potassium periodate. 
     
     
       5. The system of  claim 1  having a pH ranges from 9 to 12. 
     
     
       6. The system of  claim 1  wherein the level of the cyanate salt ranges from 0.2 weight % to 4 weight %. 
     
     
       7. The system of  claim 1  wherein the level of the oxidizing agent containing at least one peroxy-functional group ranges from 0.01 weight % to 2.0 weight %. 
     
     
       8. The system of  claim 1  further comprising d) alkyl or aryl sulfonate ions. 
     
     
       9. The system of  claim 8  wherein the aryl sulfonate ions are benzene sulfonate ions. 
     
     
       10. The system of  claim 1  wherein the noble metal is ruthenium.